I updated to Gutenberg but I had an SEO audit and my consultant recommended classic editor plugin to switch back to classic as he said Gutenberg still has some problem of compatibility.
I added the shortcode manually
Yoast is red because does not recognize anything in the article below the TOC code, so while the article is more than 300 words he only reads 78 which is up to the TOC code. Anything below it is as it is not there.
I also have a conflict with Yoast, it doesn’t read below the code so it gives me a red light for SEO optimization
